The invention is generally related to the field of forming aluminum nitride layers in semiconductor devices.
Aluminum nitride layers are used in a variety of applications in semiconductor devices. Aluminum nitride can be used as a liner in shallow trench applications. In multilevel interconnects, the metal layers are sometimes cladded with aluminum nitride. Aluminum nitride has also been used as an antireflective coating.
There are several common methods for forming aluminum nitride. One common method is sputter deposition. RF sputtering from Al2O3 targets or Al targets in an N2 ambient is used to deposit AlN on the surface of a structure. Another method used to form aluminum nitride is plasma-enhanced chemical vapor deposition (PECVD). Triamino alane and N2 are used in the PECVD process to deposit aluminum nitride on the surface. Extremely high temperatures (e.g.,  greater than 1400xc2x0 C.) an also form AlN directly from Al2O3 in the presence of carbon, hydrogen, and nitrogen.
As the density of semiconductor devices increases, the demands on interconnect layers for connecting the semiconductor devices to each other also increases. In a conventional interconnect process, the aluminum (and any barrier metals) are deposited, patterned, and etched to form the interconnect lines. A diffusion barrier layer, such as SiO2 or SiN, is then deposited over the interconnect lines to prevent diffusion of impurities.
After the dielectric liner is deposited, an interlevel dielectric (ILD) is formed between the interconnect lines. In order to meet the performance demands (i.e., reduced capacitance) of the interconnect lines, spin-on low dielectric constant (low-k) materials and vapor deposited dielectrics are being employed in at least a portion of the ILD. Low-k materials are generally defined as those materials having a dielectric constant below that of silicon dioxide.
There is a desire to decrease the spacing between interconnect lines as the semiconductor devices become more dense. The deposited dielectric diffusion barrier on the sidewalls of the aluminum interconnect lines further reduces the spacing between interconnect lines. This, in turn, reduces the amount of low-k material that can be used for gap fill between the interconnect lines. Accordingly, a thinner diffusion barrier is desired.
The invention is a method of forming an aluminum nitride thin film in an integrated circuit. A thin aluminum nitride layer is formed at the surface of an aluminum layer using hydrazine synthesized from hydrazine cyanurate.
An advantage of the invention is providing an aluminum nitride thin film with a less hazardous process.
This and other advantages will be apparent to those of ordinary skill in the art having reference to the specification in conjunction with the drawings.